1. Field
An embodiment of the present invention relates to a quantum random number generator.
2. Description of the Related Art
A random number generator has a large number of applications such as numerical simulation, codes, quantum cryptography, lottery and the like. When the random number generator is based on software and/or hardware, such a system is deterministic system. Thus, when an initial value and a peripheral environment variable are known, a random number sequence may be estimated, and it is difficult to regard the random number generator as a true random number generator. On the other hand, when the random number generator is based on a quantum physics, since a random number sequence may not be estimated, the random number generator may be regarded as the true random number generator. A quantum random number generator is used for quantum communications. For ultrahigh speed quantum communications, an ultrahigh speed true quantum random number generator is required. A conventional quantum random number generator is formed of a single photon light source and a single photon detector. Because the single photon detector is driven at a low speed of several decades of MHz, the speed of a conventional quantum random number generator is several decades of MHz.
A quantum random number generator (the U.S. Pat. No. 8,554,814 B2) based on a quantum phase noise of a laser light source was proposed as the quantum random number generator in which the single photon detector is not used. The suggested quantum random number generator converts a random phase noise of a light source into a amplitude noise by using a planar light wave circuit mach-zhender interferometer and measures the converted amplitude noise by an optical detector to form an ultrahigh speed quantum random number generating system of GHz.
However, the suggested quantum random number generator requires a mach-zhender interferometer in which a time difference between two paths is large (˜500 ps) in order to measure a phase noise of a light source. Furthermore, temperature must be controlled in order to stably drive the mach-zhender interferometer and only one output is made.